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A spectroscopic study of adducts of heterocyclic nitrogen bases with nickel(II) chelates of 2-methyl-5-nitrophenylthiocarbazone
SpcctrochimcaAera,Vol
42A
0584-8539/863300 + 000 @ 1986kr~on PRSS Ltd
No 5-p~ 693-694,1986
PnotedmGrcatBntPIo
RESEARCH
NOTE
A SPECTROSCOPIC STUDY OF ADDUCTS OF HETEROCYCLIC NITROGEN BASES WITH NICKEL(I1) CHELATES OF 2-METHYL-5NITROPHENYLTHIOCARBAZONE* K S MATH,? T SURESH and T M AMINABHAVI Department of Chermstry, Kamatak Unnerslty, Dhanvad 580003, India (Receaued 25 October 1985, accepted 26 November 1985) Abstract-A
spectrophotometnc method was employed to study the adduct formation constants of a few typical bases with mckel(II) chelates of 2-methyl-5-n1trophenylthmcarbazone MonobasK: bases such as pyndlne and methyl-subsmuted pyndmes form pentacoord1nated adducts with a stolchlometry of 1 1 for metal chelate-base The d1basr bases such as l,l@phenanthrohne, 2,2’-blpyndyl, etc also exhibit 1 1 sto1chlomeu-v a1v1nahexacoordmated adducts The exuenmental results are duetused 1nterms of the bas1cltv and stenc factors of the vanous bases
INTRODUCTION
RESULTS AND DISCUSSION
In contlnuatlon of earlier research [ 1-33 deahng with heterocycl1c bases of metal chelates, herein we report the results of reactions between heterocycbc bases and nlckel(I1) chelates of 2-methyl-S-n1trophenylthmcarbaaone [abbrevmted as N1(2MSNTC)1] Various reagents used were pyndme, 2plcohne, 3-psohne, clplcolme, 2,6-lutldme, 2,41uudme, 2,4,6colhdlne, 2,2’-hpyndyl, l,l@phenanthrohne and 2,9-neocupro1n A spectrophotometnc method was employed to determme the formation constants of the adducts formed 1n chloroform at 25°C The results are discussed 1n relation to the bas1cny of the adducmg bases and the chelating ability of the bldentate bases
The absorption spectra were measured 1n the vlslble repon around 400-800 nm using chloroform as a reference at a concentration of lo-’ M A typical spectrum for N1(2MSNTC), 1s shown 1n Rg 1 The brown coloured chloroform solution of N1(2MSNTC)1 has multiple bands 1n the vls1ble reaon, namely 1, around 670 (e,, N 14 000), 545 (em1 _ 19 000) and 420 nm (s,,,, w 42 000) The addition of nitrogen bases to N1(2MSNTC)1 produced a pink coloured adduct havmg absorption bands around 420 and 5OOnm Measurements at wavelengths of 500 and 675 nm gave smular results However, the absorption at 675 nm was smtable for analysis because at tms value only the chelate absorbs Therefore, absorption values at 675 nm were plotted as a function of pB to obtam s1gmo1dalcurves The values of A, were obtamed from the extrapolation of these curves which are used 1n the calculation of loggf values using
EXPERIMENTAL A Bausch and Lomb Spectronlc 2ooO recording spectrophotometer was used for absorbance measurements The method described by Scorr and SPELL [4] was used to prepare d1-(2-methyl-5-n1trophenyl)thmcarbaaone The crude product was pun&d by extracting 1t with 5 % sodium carbonate solution and acidifying the carbonate solution to get the pure solid (m p 149°C) Pyndlne (Rsher) and plcolmes (Eastman) were puntied by d1stlllatlon after drymg over KOH The remammg chermcals, namely l,lO-phenanthrohne (G Fredenck Srmth Co), neocuproin and ethylenedlamme (BDH), chloroform (E Merck) etc, were used as such The N1(2MSNTC)1 was prepared by dlssolvmg a known amount of the nickel perchlorate (* 1 g) in acetate buffer (pH = 6) and mumg 1t with an appropnate amount of reagent m alcohohc solution The preclprtate obtamed was thoroughly washed wtth water and subsequently Hnth a few mdhbtres of alcohol, rt was then audned The quantltatlve analysis of mckel agreed well with the calculated results *Based on the Ph D thesis of T SURESHsubmitted to Kamatak University (1985) t Author to whom correspondence should be addressed
log/?? = --n log[B] +log
(1)
where n 1s the number of base adducts, B, attached to the chelate, A,, and Ati are, respectively, the absorbances due to chelates and adducts and A IS the absorbance due to the chelate and adduct eqmhbnum rmxture In the case of hdentate hgands, in addition to the slope of unity found from Bqn (I), the mole ratio method was also used to confirm the ratio of base to chelate It was gratifying to find that the absorption spectrum of N1(2MSNTC)1 d1d not change upon addition of 2-plcohne, 2,6_lut1dme, 2,4lut1d1neand 2,9-neocuproln 1nd1catmg the absence of adduct formation The expenmental data are gven 1n Table 1 The stabtitles of mckel(II) adducts urlth monodentate bases such as pyndlne and pzohnes increase steaddy with the increase 1npK, values as expected In the case of Zplcohne no adduct was formed, indicative of stenc hmdrance due to the methyl group 1n the o-position Smularly, lut1d1nes and colbdme did not form adducts In an earber study [2] on nickel(H) dlthmonates, MATHand FREISER[2] observed very s1mdar trends but their values were mgher than the present results ms rmght have been due to the absence of stenc
693
694
Research Note
WAVELENGTH
IN NM
IGg 1 Absorption spectra of a nuxture of N1(2M5NTQ +2,2’-blpyndyl m chloroform at 25°C [2,2’tnpyndyl] x lo6 = (a) 0 00; (b) 1 34, (c) 2 69, (d) 4 03, (e) 5 38, (f) 6 72, (g) 8 07, (h) 10 75, (I) 13 44, (J) 21 51 and (k) 40 33
Table 1 Adduct formatIon constants of mtrogen bases with mckel(I1) chelates of 2. methyl-5-mtrophenylthmcarbazone log B.“dfor
Slope
Reagents
PK,
Pyridme 2-Picohne 3-Plcohne CPxohne 2,dLuticlme 2,4-Lutldme 2,2’-Bipyridyl l,lO-Phenanthrohne 2,9-Neocuprom Ethylenedauume
520 590 568 608 495 672 440 495 585 684
(n)
N1(2M5NTC)I
NI(O’ITC)~*
1
068 NAS 092 108 NA NA 518 524 NA 344
-1 78 NA -122
1 1 1 1 1
NA NA 320 437 NA 226
NIDz, t 108 -042
132 145 -060 429 590 3 86
lNlckel(II) orthotolylthmcarbazonate tNickel(II) dlthlzonate $.N A.-no adduct formation
groups on the chelate rmgs However, our most recent data [3] mdaxted negative values for the adducts of mckel(I1) orthotolylthmcarbazonate In the case of bidentate hgands such as 2,2’-bipyndyl, l,lOphenanthrohne and ethylenediamme it appears that adduct formation with tndentate bases IS not very adversely mBuenced by a methyl group m the o-position of 2MSNTC This nught be due to the rearrangement of the chelate rings in order to provide a czs-positIon for the hdentate bases
of Atonuc Energy, Bombay, for the financial support of this study Department
REFERENCES K S MATH,G S ARKASALI and T M AMINABHAVI, J
Chem Eng Data 30,447 (1985) K S MATH and H FREISER,Analyt
Chem 41, 1682
(1969)
K S MATHand T SURESH,Talanta 32, 811 (1985) A SCOTT and C R SPELL,J Am them Sot 68, 328 Acknowledgement-T
SURESHacknowledges
his thanks to
(1946)
42A
0584-8539/863300 + 000 @ 1986kr~on PRSS Ltd
No 5-p~ 693-694,1986
PnotedmGrcatBntPIo
RESEARCH
NOTE
A SPECTROSCOPIC STUDY OF ADDUCTS OF HETEROCYCLIC NITROGEN BASES WITH NICKEL(I1) CHELATES OF 2-METHYL-5NITROPHENYLTHIOCARBAZONE* K S MATH,? T SURESH and T M AMINABHAVI Department of Chermstry, Kamatak Unnerslty, Dhanvad 580003, India (Receaued 25 October 1985, accepted 26 November 1985) Abstract-A
spectrophotometnc method was employed to study the adduct formation constants of a few typical bases with mckel(II) chelates of 2-methyl-5-n1trophenylthmcarbazone MonobasK: bases such as pyndlne and methyl-subsmuted pyndmes form pentacoord1nated adducts with a stolchlometry of 1 1 for metal chelate-base The d1basr bases such as l,l@phenanthrohne, 2,2’-blpyndyl, etc also exhibit 1 1 sto1chlomeu-v a1v1nahexacoordmated adducts The exuenmental results are duetused 1nterms of the bas1cltv and stenc factors of the vanous bases
INTRODUCTION
RESULTS AND DISCUSSION
In contlnuatlon of earlier research [ 1-33 deahng with heterocycl1c bases of metal chelates, herein we report the results of reactions between heterocycbc bases and nlckel(I1) chelates of 2-methyl-S-n1trophenylthmcarbaaone [abbrevmted as N1(2MSNTC)1] Various reagents used were pyndme, 2plcohne, 3-psohne, clplcolme, 2,6-lutldme, 2,41uudme, 2,4,6colhdlne, 2,2’-hpyndyl, l,l@phenanthrohne and 2,9-neocupro1n A spectrophotometnc method was employed to determme the formation constants of the adducts formed 1n chloroform at 25°C The results are discussed 1n relation to the bas1cny of the adducmg bases and the chelating ability of the bldentate bases
The absorption spectra were measured 1n the vlslble repon around 400-800 nm using chloroform as a reference at a concentration of lo-’ M A typical spectrum for N1(2MSNTC), 1s shown 1n Rg 1 The brown coloured chloroform solution of N1(2MSNTC)1 has multiple bands 1n the vls1ble reaon, namely 1, around 670 (e,, N 14 000), 545 (em1 _ 19 000) and 420 nm (s,,,, w 42 000) The addition of nitrogen bases to N1(2MSNTC)1 produced a pink coloured adduct havmg absorption bands around 420 and 5OOnm Measurements at wavelengths of 500 and 675 nm gave smular results However, the absorption at 675 nm was smtable for analysis because at tms value only the chelate absorbs Therefore, absorption values at 675 nm were plotted as a function of pB to obtam s1gmo1dalcurves The values of A, were obtamed from the extrapolation of these curves which are used 1n the calculation of loggf values using
EXPERIMENTAL A Bausch and Lomb Spectronlc 2ooO recording spectrophotometer was used for absorbance measurements The method described by Scorr and SPELL [4] was used to prepare d1-(2-methyl-5-n1trophenyl)thmcarbaaone The crude product was pun&d by extracting 1t with 5 % sodium carbonate solution and acidifying the carbonate solution to get the pure solid (m p 149°C) Pyndlne (Rsher) and plcolmes (Eastman) were puntied by d1stlllatlon after drymg over KOH The remammg chermcals, namely l,lO-phenanthrohne (G Fredenck Srmth Co), neocuproin and ethylenedlamme (BDH), chloroform (E Merck) etc, were used as such The N1(2MSNTC)1 was prepared by dlssolvmg a known amount of the nickel perchlorate (* 1 g) in acetate buffer (pH = 6) and mumg 1t with an appropnate amount of reagent m alcohohc solution The preclprtate obtamed was thoroughly washed wtth water and subsequently Hnth a few mdhbtres of alcohol, rt was then audned The quantltatlve analysis of mckel agreed well with the calculated results *Based on the Ph D thesis of T SURESHsubmitted to Kamatak University (1985) t Author to whom correspondence should be addressed
log/?? = --n log[B] +log
(1)
where n 1s the number of base adducts, B, attached to the chelate, A,, and Ati are, respectively, the absorbances due to chelates and adducts and A IS the absorbance due to the chelate and adduct eqmhbnum rmxture In the case of hdentate hgands, in addition to the slope of unity found from Bqn (I), the mole ratio method was also used to confirm the ratio of base to chelate It was gratifying to find that the absorption spectrum of N1(2MSNTC)1 d1d not change upon addition of 2-plcohne, 2,6_lut1dme, 2,4lut1d1neand 2,9-neocuproln 1nd1catmg the absence of adduct formation The expenmental data are gven 1n Table 1 The stabtitles of mckel(II) adducts urlth monodentate bases such as pyndlne and pzohnes increase steaddy with the increase 1npK, values as expected In the case of Zplcohne no adduct was formed, indicative of stenc hmdrance due to the methyl group 1n the o-position Smularly, lut1d1nes and colbdme did not form adducts In an earber study [2] on nickel(H) dlthmonates, MATHand FREISER[2] observed very s1mdar trends but their values were mgher than the present results ms rmght have been due to the absence of stenc
693
694
Research Note
WAVELENGTH
IN NM
IGg 1 Absorption spectra of a nuxture of N1(2M5NTQ +2,2’-blpyndyl m chloroform at 25°C [2,2’tnpyndyl] x lo6 = (a) 0 00; (b) 1 34, (c) 2 69, (d) 4 03, (e) 5 38, (f) 6 72, (g) 8 07, (h) 10 75, (I) 13 44, (J) 21 51 and (k) 40 33
Table 1 Adduct formatIon constants of mtrogen bases with mckel(I1) chelates of 2. methyl-5-mtrophenylthmcarbazone log B.“dfor
Slope
Reagents
PK,
Pyridme 2-Picohne 3-Plcohne CPxohne 2,dLuticlme 2,4-Lutldme 2,2’-Bipyridyl l,lO-Phenanthrohne 2,9-Neocuprom Ethylenedauume
520 590 568 608 495 672 440 495 585 684
(n)
N1(2M5NTC)I
NI(O’ITC)~*
1
068 NAS 092 108 NA NA 518 524 NA 344
-1 78 NA -122
1 1 1 1 1
NA NA 320 437 NA 226
NIDz, t 108 -042
132 145 -060 429 590 3 86
lNlckel(II) orthotolylthmcarbazonate tNickel(II) dlthlzonate $.N A.-no adduct formation
groups on the chelate rmgs However, our most recent data [3] mdaxted negative values for the adducts of mckel(I1) orthotolylthmcarbazonate In the case of bidentate hgands such as 2,2’-bipyndyl, l,lOphenanthrohne and ethylenediamme it appears that adduct formation with tndentate bases IS not very adversely mBuenced by a methyl group m the o-position of 2MSNTC This nught be due to the rearrangement of the chelate rings in order to provide a czs-positIon for the hdentate bases
of Atonuc Energy, Bombay, for the financial support of this study Department
REFERENCES K S MATH,G S ARKASALI and T M AMINABHAVI, J
Chem Eng Data 30,447 (1985) K S MATH and H FREISER,Analyt
Chem 41, 1682
(1969)
K S MATHand T SURESH,Talanta 32, 811 (1985) A SCOTT and C R SPELL,J Am them Sot 68, 328 Acknowledgement-T
SURESHacknowledges
his thanks to
(1946)